Method for transmitting downlink control information for sidelink scheduling in wireless communication system and terminal using same

ABSTRACT

Provided are a method for transmitting downlink control information for sidelink scheduling in a wireless communication system and a wireless apparatus using the method. The method is characterized by: generating sidelink SPS activation/release DCI for indicating sidelink semi-persistent scheduling (SPS) activation or release; and transmitting the sidelink SPS activation/release DCI to a terminal, wherein the sidelink SPS activation/release DCI further comprises a sidelink SPS activation/release field and a sidelink SPS configuration index field not present in sidelink dynamic DCI which is for dynamically scheduling the sidelink.

BACKGROUND OF THE INVENTION Field of the invention

The present invention relates to wireless communication and, mostparticularly, to a method for transmitting downlink control informationfor sidelink scheduling in a wireless communication system and aterminal using the same.

Related Art

In International Telecommunication Union Radio communication sector(ITU-R), a standardization task for International MobileTelecommunication (IMT)-Advanced, that is, the next-generation mobilecommunication system since the third generation, is in progress.IMT-Advanced sets its goal to support Internet Protocol (IP)-basedmultimedia services at a data transfer rate of 1 Gbps in the stop andslow-speed moving state and of 100 Mbps in the fast-speed moving state.

For example, 3^(rd) Generation Partnership Project (3GPP) is a systemstandard to satisfy the requirements of IMT-Advanced and is preparingfor LTE-Advanced improved from Long Term Evolution (LTE) based onOrthogonal Frequency Division Multiple Access (OFDMA)/SingleCarrier-Frequency Division Multiple Access (SC-FDMA) transmissionschemes. LTE-Advanced is one of strong candidates for IMT-Advanced.

There is a growing interest in a Device-to-Device (D22) technology inwhich devices perform direct communication. In particular, D2D has beenin the spotlight as a communication technology for a public safetynetwork. A commercial communication network is rapidly changing to LTE,but the current public safety network is basically based on the 2Gtechnology in terms of a collision problem with existing communicationstandards and a cost. Such a technology gap and a need for improvedservices are leading to efforts to improve the public safety network.

The public safety network has higher service requirements (reliabilityand security) than the commercial communication network. In particular,if coverage of cellular communication is not affected or available, thepublic safety network also requires direct communication betweendevices, that is, D2D operation.

D2D operation may have various advantages in that it is communicationbetween devices in proximity. For example, D2D UE has a high transferrate and a low delay and may perform data communication. Furthermore, inD2D operation, traffic concentrated on a base station can bedistributed. If D2D UE plays the role of a relay, it may also play therole of extending coverage of a base station.

The above-described D2D communication may be expanded and applied tosignal transmission and/or reception between vehicles. Mostparticularly, vehicle-related communication is referred to asvehicle-to-everything (V2X) communication.

In V2X, the term ‘X’ may refer to a pedestrian, a vehicle, aninfrastructure/network, and so on, which may be respectively indicatedas V2P, V2V, and V2I/N.

Meanwhile, a wireless communication system may transmit signals by usingsemi-persistent scheduling (SPS). Herein, semi-persistent scheduling(SPS) corresponds to a scheduling method that first determines inadvance a cycle period for transmitting a signal through a higher layersignal and then transmits a signal by using a modulation and codingscheme (MCS), a resource, and so on, which are indicated by a controlchannel according to the pre-determined cycle period, while directing(or instructing) activation of SPS through the control channel whenannouncing (or notifying) a specific resource. The signal transmissionaccording to the above-described SPS may also be used in the V2Xcommunication.

Meanwhile, a device-to-device direct link may also be referred to as asidelink. Both a dynamic method and a semi-persistent method may be usedas the scheduling method in a sidelink. At this point, sincecharacteristics of downlink control information that is used fordynamically performing scheduling are different from characteristics ofdownlink control information that is used for semi-persistentlyperforming scheduling, it may not be preferable to use downlink controlinformation configured to have the same format.

SUMMARY OF THE INVENTION

An object that is to be achieved by the present invention is to providea method for transmitting downlink control information for sidelinkscheduling in a wireless communication system and a terminal using thesame.

In one aspect, provided is a method for transmitting downlink controlinformation for sidelink scheduling in a wireless communication system.The method includes generating a sidelink SPS activation/release DCIinstructing an activation or release of a sidelink semi-persistentscheduling (SPS) and transmitting the sidelink SPS activation/releaseDCI to a user equipment (UE). The sidelink SPS activation/release DCIfurther includes a sidelink SPS configuration index field and a sidelinkSPS activation/release field that do not exist in a sidelink dynamicDCI, the sidelink dynamic DCI performing dynamic scheduling of asidelink.

The sidelink SPS configuration index field may include informationindicating one of a plurality of sidelink SPS configurations.

A total bit size of the sidelink SPS activation/release DCI may belarger than a total bit size of the sidelink dynamic DCI.

The sidelink SPS configuration index field may be configured of 3 bits.

The sidelink SPS activation/release field may be configured of 1 bit.

In another aspect, provided is a wireless device. The wireless deviceincludes a radio frequency (RF) unit transmitting and receiving radiosignals and a processor being operatively connected to the RF unit. Theprocessor is configured to generate a sidelink SPS activation/releaseDCI instructing an activation or release of a sidelink semi-persistentscheduling (SPS), and to transmit the sidelink SPS activation/releaseDCI to a user equipment (UE). The sidelink SPS activation/release DCIfurther includes a sidelink SPS configuration index field and a sidelinkSPS activation/release field that do not exist in a sidelink dynamicDCI, the sidelink dynamic DCI performing dynamic scheduling of asidelink.

A plurality of SPS processes/configurations may be configured in asidelink. According to the present invention, unlike a DCI thatdynamically schedules a sidelink, a DCI activating/releasing the SPS inthe sidelink may additionally include a sidelink SPS configuration indexfield announcing for which particular SPS configuration thecorresponding activation/release is intended, and a sidelink SPSconfiguration activation/release field. Therefore, even in a case wherea plurality of sidelink SPS configurations exist, the user equipment (orterminal) and the base station may perform the sidelink SPS processwithout any ambiguity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane.

FIG. 3 is a diagram showing a wireless protocol architecture for acontrol plane.

FIG. 4 shows a basic structure for ProSe.

FIG. 5 shows the deployment examples of types of UE performing ProSedirect communication and cell coverage.

FIG. 6 shows a user plane protocol stack for ProSe direct communication.

FIG. 7 shows a PC 5 interface for D2D discovery.

FIG. 8 shows an example of an existing uplink SPS process.

FIG. 9 shows an example of a case where an uplink SPS process is appliedto the V2X.

FIG. 10 shows a UE operation method according to uplink SPS.

FIG. 11 is a diagram showing a comparison between the existing (VoIP)uplink SPS activation/release DCI (first DCI) and the V2X uplink SPSactivation/release DCI (second DCI) by applying the [Proposed Method #2]

FIG. 12 shows an example of a method for interpreting a specific fieldwhen decoding the first DCI and the second DCI.

FIG. 13 is a diagram showing a comparison between a DCI for dynamicallyscheduling a sidelink channel (DCI for Dynamic scheduling (V2X SLdynamic DCI)) and a sidelink channel SPS activation/release DCI (V2X SLSPS activation/release DCI).

FIG. 14 shows an example of a method for transmitting downlink controlinformation for sidelink scheduling according to another exemplaryembodiment of the present invention.

FIG. 15 shows an example of a method for performing an SPS processaccording to yet another exemplary embodiment of the present invention.

FIG. 16 describes an example of validating a DCI as a DCI format for V2Xsidelink SPS activation/release or as a V2X sidelink dynamic DCI.

FIG. 17 shows an example where 2 reports are used at the same time.

FIG. 18 is a block diagram illustrating a UE in which the embodiments ofthe present invention are implemented.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a wireless communication system.

The wireless communication system may be referred to as an Evolved-UMTSTerrestrial Radio Access Network (E-UTRAN) or a Long Term Evolution(LTE)/LTE-A system, for example.

The E-UTRAN includes at least one base station (BS) 20 which provides acontrol plane and a user plane to a user equipment (UE) 10. The UE 10may be fixed or mobile, and may be referred to as another terminology,such as a mobile station (MS), a user terminal (UT), a subscriberstation (SS), a mobile terminal (MT), a wireless device, etc. The BS 20is generally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as an evolved node-B (eNB), abase transceiver system (BTS), an access point, etc.

The BSs 20 are interconnected by means of an X2 interface. The BSs 20are also connected by means of an S1 interface to an evolved packet core(EPC) 30, more specifically, to a mobility management entity (MME)through S1-MME and to a serving gateway (S-GW) through S1-U.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway(P-GW). The MME has access information of the UE or capabilityinformation of the UE, and such information is generally used formobility management of the UE. The S-GW is a gateway having an E-UTRANas an end point. The P-GW is a gateway having a PDN as an end point.

Layers of a radio interface protocol between the UE and the network canbe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. Among them, a physical (PHY) layer belonging to the first layerprovides an information transfer service by using a physical channel,and a radio resource control (RRC) layer belonging to the third layerserves to control a radio resource between the UE and the network. Forthis, the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane. FIG. 3 is a diagram showing a wireless protocol architecture fora control plane. The user plane is a protocol stack for user datatransmission. The control plane is a protocol stack for control signaltransmission.

Referring to FIGS. 2 and 3, a PHY layer provides an upper layer with aninformation transfer service through a physical channel. The PHY layeris connected to a medium access control (MAC) layer which is an upperlayer of the PHY layer through a transport channel. Data is transferredbetween the MAC layer and the PHY layer through the transport channel.

The transport channel is classified according to how and with whatcharacteristics data is transferred through a radio interface.

Data is moved between different PHY layers, that is, the PHY layers of atransmitter and a receiver, through a physical channel. The physicalchannel may be modulated according to an Orthogonal Frequency DivisionMultiplexing (OFDM) scheme, and use the time and frequency as radioresources.

The functions of the MAC layer include mapping between a logical channeland a transport channel and multiplexing and demultiplexing to atransport block that is provided through a physical channel on thetransport channel of a MAC Service Data Unit (SDU) that belongs to alogical channel. The MAC layer provides service to a Radio Link Control(RLC) layer through the logical channel.

The functions of the RLC layer include the concatenation, segmentation,and reassembly of an RLC SDU. In order to guarantee various types ofQuality of Service (QoS) required by a Radio Bearer (RB), the RLC layerprovides three types of operation mode: Transparent Mode (TM),Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provideserror correction through an Automatic Repeat Request (ARQ).

The RRC layer is defined only on the control plane. The RRC layer isrelated to the configuration, reconfiguration, and release of radiobearers, and is responsible for control of logical channels, transportchannels, and PHY channels. An RB means a logical route that is providedby the first layer (PHY layer) and the second layers (MAC layer, the RLClayer, and the PDCP layer) in order to transfer data between UE and anetwork.

The function of a Packet Data Convergence Protocol (PDCP) layer on theuser plane includes the transfer of user data and header compression andciphering. The function of the PDCP layer on the user plane furtherincludes the transfer and encryption/integrity protection of controlplane data.

What an RB is configured means a process of defining the characteristicsof a wireless protocol layer and channels in order to provide specificservice and configuring each detailed parameter and operating method. AnRB can be divided into two types of a Signaling RB (SRB) and a Data RB(DRB). The SRB is used as a passage through which an RRC message istransmitted on the control plane, and the DRB is used as a passagethrough which user data is transmitted on the user plane.

If RRC connection is established between the RRC layer of UE and the RRClayer of an E-UTRAN, the UE is in the RRC connected state. If not, theUE is in the RRC idle state.

A downlink transport channel through which data is transmitted from anetwork to UE includes a broadcast channel (BCH) through which systeminformation is transmitted and a downlink shared channel (SCH) throughwhich user traffic or control messages are transmitted. Traffic or acontrol message for downlink multicast or broadcast service may betransmitted through the downlink SCH, or may be transmitted through anadditional downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from UE to a networkincludes a random access channel (RACH) through which an initial controlmessage is transmitted and an uplink shared channel (SCH) through whichuser traffic or control messages are transmitted.

Logical channels that are placed over the transport channel and that aremapped to the transport channel include a broadcast control channel(BCCH), a paging control channel (PCCH), a common control channel(CCCH), a multicast control channel (MCCH), and a multicast trafficchannel (MTCH).

The physical channel includes several OFDM symbols in the time domainand several subcarriers in the frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. An RB is a resourcesallocation unit, and includes a plurality of OFDM symbols and aplurality of subcarriers. Furthermore, each subframe may use specificsubcarriers of specific OFDM symbols (e.g., the first OFDM symbol) ofthe corresponding subframe for a physical downlink control channel(PDCCH), that is, an L1/L2 control channel. A Transmission Time Interval(TTI) is a unit time for subframe transmission.

The RRC state means whether or not the RRC layer of UE is logicallyconnected to the RRC layer of the E-UTRAN. A case where the RRC layer ofUE is logically connected to the RRC layer of the E-UTRAN is referred toas an RRC connected state. A case where the RRC layer of UE is notlogically connected to the RRC layer of the E-UTRAN is referred to as anRRC idle state. The E-UTRAN may check the existence of corresponding UEin the RRC connected state in each cell because the UE has RRCconnection, so the UE may be effectively controlled. In contrast, theE-UTRAN is unable to check UE in the RRC idle state, and a Core Network(CN) manages UE in the RRC idle state in each tracking area, that is,the unit of an area greater than a cell. That is, the existence ornon-existence of UE in the RRC idle state is checked only for each largearea. Accordingly, the UE needs to shift to the RRC connected state inorder to be provided with common mobile communication service, such asvoice or data.

When a user first powers UE, the UE first searches for a proper cell andremains in the RRC idle state in the corresponding cell. The UE in theRRC idle state establishes RRC connection with an E-UTRAN through an RRCconnection procedure when it is necessary to set up the RRC connection,and shifts to the RRC connected state. A case where UE in the RRC idlestate needs to set up RRC connection includes several cases. Forexample, the cases may include a need to send uplink data for a reason,such as a call attempt by a user, and to send a response message as aresponse to a paging message received from an E-UTRAN.

A Non-Access Stratum (NAS) layer placed over the RRC layer performsfunctions, such as session management and mobility management.

In the NAS layer, in order to manage the mobility of UE, two types ofstates: EPS Mobility Management-REGISTERED (EMM-REGISTERED) andEMM-DEREGISTERED are defined. The two states are applied to UE and theMME. UE is initially in the EMM-DEREGISTERED state. In order to access anetwork, the UE performs a process of registering it with thecorresponding network through an initial attach procedure. If the attachprocedure is successfully performed, the UE and the MME become theEMM-REGISTERED state.

In order to manage signaling connection between UE and the EPC, twotypes of states: an EPS Connection Management (ECM)-IDLE state and anECM-CONNECTED state are defined. The two states are applied to UE andthe MME. When the UE in the ECM-IDLE state establishes RRC connectionwith the E-UTRAN, the UE becomes the ECM-CONNECTED state. The MME in theECM-IDLE state becomes the ECM-CONNECTED state when it establishes Siconnection with the E-UTRAN. When the UE is in the ECM-IDLE state, theE-UTRAN does not have information about the context of the UE.Accordingly, the UE in the ECM-IDLE state performs procedures related toUE-based mobility, such as cell selection or cell reselection, without aneed to receive a command from a network. In contrast, when the UE is inthe ECM-CONNECTED state, the mobility of the UE is managed in responseto a command from a network. If the location of the UE in the ECM-IDLEstate is different from a location known to the network, the UE informsthe network of its corresponding location through a tracking area updateprocedure.

The D2D operation will now be described. In 3GPP LTE-A, the servicerelated to D2D operation is called proximity based service (ProSe).Hereinafter, ProSe is equivalent to D2D operation and ProSe may beinterchanged with D2D operation. ProSe will now be described.

The ProSe includes ProSe direction communication and ProSe directdiscovery. The ProSe direct communication is communication performedbetween two or more proximate UEs. The UEs may perform communication byusing a protocol of a user plane. A ProSe-enabled UE implies a UEsupporting a procedure related to a requirement of the ProSe. Unlessotherwise specified, the ProSe-enabled UE includes both of a publicsafety UE and a non-public safety UE. The public safety UE is a UEsupporting both of a function specified for a public safety and a ProSeprocedure, and the non-public safety UE is a UE supporting the ProSeprocedure and not supporting the function specified for the publicsafety.

ProSe direct discovery is a process for discovering anotherProSe-enabled UE adjacent to ProSe-enabled UE. In this case, only thecapabilities of the two types of ProSe-enabled UE are used. EPC-levelProSe discovery means a process for determining, by an EPC, whether thetwo types of ProSe-enabled UE are in proximity and notifying the twotypes of ProSe-enabled UE of the proximity.

Hereinafter, for convenience, the ProSe direct communication may bereferred to as D2D communication, and the ProSe direct discovery may bereferred to as D2D discovery.

FIG. 4 shows a basic structure for ProSe.

Referring to FIG. 4, the basic structure for ProSe includes an E-UTRAN,an EPC, a plurality of types of UE including a ProSe applicationprogram, a ProSe application server (a ProSe APP server), and a ProSefunction.

The EPC represents an E-UTRAN core network configuration. The EPC mayinclude an MME, an S-GW, a P-GW, a policy and charging rules function(PCRF), a home subscriber server (HSS) and so on.

The ProSe APP server is a user of a ProSe capability for producing anapplication function. The ProSe APP server may communicate with anapplication program within UE. The application program within UE may usea ProSe capability for producing an application function.

The ProSe function may include at least one of the followings, but isnot necessarily limited thereto.

Interworking via a reference point toward the 3^(rd) party applications

Authorization and configuration of UE for discovery and directcommunication

Enable the functionality of EPC level ProSe discovery

ProSe related new subscriber data and handling of data storage, and alsohandling of the ProSe identities

Security related functionality

Provide control towards the EPC for policy related functionality

Provide functionality for charging (via or outside of the EPC, e.g.,offline charging)

A reference point and a reference interface in the basic structure forProSe are described below.

PC1: a reference point between the ProSe application program within theUE and the ProSe application program within the ProSe APP server. Thisis used to define signaling requirements in an application dimension.

PC2: a reference point between the ProSe APP server and the ProSefunction. This is used to define an interaction between the ProSe APPserver and the ProSe function. The update of application data in theProSe database of the ProSe function may be an example of theinteraction.

PC3: a reference point between the UE and the ProSe function. This isused to define an interaction between the UE and the ProSe function. Aconfiguration for ProSe discovery and communication may be an example ofthe interaction.

PC4: a reference point between the EPC and the ProSe function. This isused to define an interaction between the EPC and the ProSe function.The interaction may illustrate the time when a path for 1:1communication between types of UE is set up or the time when ProSeservice for real-time session management or mobility management isauthenticated.

PC5: a reference point used for using control/user plane for discoveryand communication, relay, and 1:1 communication between types of UE.

PC6: a reference point for using a function, such as ProSe discovery,between users belonging to different PLMNs.

SGi: this may be used to exchange application data and types ofapplication dimension control information.

The D2D operation may be supported both when UE is serviced within thecoverage of a network (cell) or when it is out of coverage of thenetwork.

FIG. 5 shows the deployment examples of types of UE performing ProSedirect communication and cell coverage.

Referring to FIG. 5(a), types of UE A and B may be placed outside cellcoverage. Referring to FIG. 5(b), UE A may be placed within cellcoverage, and UE B may be placed outside cell coverage. Referring toFIG. 5(c), types of UE A and B may be placed within single cellcoverage. Referring to FIG. 5(d), UE A may be placed within coverage ofa first cell, and UE B may be placed within coverage of a second cell.ProSe direct communication may be performed between types of UE placedat various positions as in FIG. 5.

<Radio Resource Allocation for D2D Communication (ProSe DirectCommunication)>.

At least one of the following two modes may be used for resourceallocation for D2D communication.

1. Mode 1

Mode 1 is mode in which resources for ProSe direct communication arescheduled by an eNB. UE needs to be in the RRC_CONNECTED state in orderto send data in accordance with mode 1. The UE requests a transmissionresource from an eNB. The eNB performs scheduling assignment andschedules resources for sending data. The UE may send a schedulingrequest to the eNB and send a ProSe Buffer Status Report (BSR). The eNBhas data to be subjected to ProSe direct communication by the UE basedon the ProSe BSR and determines that a resource for transmission isrequired.

2. Mode 2

Mode 2 is mode in which UE directly selects a resource. UE directlyselects a resource for ProSe direct communication in a resource pool.The resource pool may be configured by a network or may have beenpreviously determined.

Meanwhile, if UE has a serving cell, that is, if the UE is in theRRC_CONNECTED state with an eNB or is placed in a specific cell in theRRC_IDLE state, the UE is considered to be placed within coverage of theeNB.

If UE is placed outside coverage, only mode 2 may be applied. If the UEis placed within the coverage, the UE may use mode 1 or mode 2 dependingon the configuration of an eNB.

If another exception condition is not present, only when an eNB performsa configuration, UE may change mode from mode 1 to mode 2 or from mode 2to mode 1.

<D2D Discovery (ProSe Direct Discovery)>

D2D discovery refers to the procedure used in a ProSe capable terminaldiscovering other ProSe capable terminals in close proximity thereto andmay be referred to as ProSe direct discovery. The information used forProSe direct discovery is hereinafter referred to as discoveryinformation.

A PC 5 interface may be used for D2D discovery. The PC 5 interfaceincludes an MAC layer, a PHY layer, and a ProSe Protocol layer, that is,a higher layer. The higher layer (the ProSe Protocol) handles thepermission of the announcement and monitoring of discovery information.The contents of the discovery information are transparent to an accessstratum (AS). The ProSe Protocol transfers only valid discoveryinformation to the AS for announcement. The MAC layer receives discoveryinformation from the higher layer (the ProSe Protocol). An IP layer isnot used to send discovery information. The MAC layer determines aresource used to announce discovery information received from the higherlayer. The MAC layer produces an MAC protocol data unit (PDU) forcarrying discovery information and sends the MAC PDU to the physicallayer. An MAC header is not added.

In order to announce discovery information, there are two types ofresource assignment.

1. Type 1

The type 1 is a method for assigning a resource for announcing discoveryinformation in a UE-not-specific manner. An eNB provides a resource poolconfiguration for discovery information announcement to types of UE. Theconfiguration may be broadcasted through the SIB. The configuration maybe provided through a UE-specific RRC message. Or the configuration maybe broadcasted through other than the RRC message in other layer or maybe provided by UE-specific signaling.

UE autonomously selects a resource from an indicated resource pool andannounces discovery information using the selected resource. The UE mayannounce the discovery information through a randomly selected resourceduring each discovery period.

2. Type 2

The type 2 is a method for assigning a resource for announcing discoveryinformation in a UE-specific manner. UE in the RRC_CONNECTED state mayrequest a resource for discovery signal announcement from an eNB throughan RRC signal. The eNB may announce a resource for discovery signalannouncement through an RRC signal. A resource for discovery signalmonitoring may be assigned within a resource pool configured for typesof UE.

An eNB 1) may announce a type 1 resource pool for discovery signalannouncement to UE in the RRC_IDLE state through the SIB. Types of UEwhose ProSe direct discovery has been permitted use the type 1 resourcepool for discovery information announcement in the RRC_IDLE state.Alternatively, the eNB 2) announces that the eNB supports ProSe directdiscovery through the SIB, but may not provide a resource for discoveryinformation announcement. In this case, UE needs to enter theRRC_CONNECTED state for discovery information announcement.

An eNB may configure that UE has to use a type 1 resource pool fordiscovery information announcement or has to use a type 2 resourcethrough an RRC signal in relation to UE in the RRC_CONNECTED state.

FIG. 6 illustrates a user-plane protocol stack for the ProSe directioncommunication.

Referring to FIG. 6, the PC 5 interface is configured of PDCH, RLC, MAC,and PHY layers.

In the ProSe direct communication, there may be no HARQ feedback. A MACheader may include a Source Layer-2 ID and a Target Layer-2 ID.

FIG. 7 illustrates a PC 5 interface for D2D discovery.

Referring to FIG. 7, the PC 5 interface is configured of a MAC layer, aPHY layer, and a ProSe Protocol layer, which corresponds to ahigher-level layer. The higher-level layer (ProSe Protocol) is in chargeof authorizing announcement (or notification) and monitoring ofdiscovery information, and content of the discovery information istransparent to Access Stratum. The ProSe Protocol allows only thediscovery information that is valid for the announcement to be deliveredto the AS.

The MAC layer receives the discovery information from the higher-levellayer. The IP layer is not used for the discovery informationtransmission. The MAC layer determines (or decides) the resource that isto be used for announcing the discovery information received from thehigher-level layer. The MAC layer generates a MAC protocol data unit(PDU), which carries the discovery information, and transmits thegenerated MAC PDU to the physical layer. Herein, a MAC header is notadded.

The above-described operation may also be applied tovehicle-to-everything (V2X). Hereinafter, a device-to-device directlylink may be referred to as a sidelink.

Hereinafter, the present invention will be described in detail.

Firstly, the semi-persistent scheduling (SPS) will be described indetail.

In the wireless communication system, the user equipment (UE) receivesscheduling information, such as DL grant, UL grant, and so on, throughthe PDCCH, and, then, based on the received scheduling information, theUE performs operations of receiving the PDSCH and transmitting thePUSCH. Generally, the UL grant and the PDSCH are received within thesame subframe. Thereafter, the PUSCH is transmitted after at least 4subframes from the subframe that has received the UL grant. In additionto such dynamic scheduling, the LTE/LTE-A also provides semi-persistentscheduling (SPS).

Downlink or uplink SPS may announce (or notify) to the UE in whichsubframes the semi-persistent transmission (PUSCH)/reception (PDSCH)is/are performed through a higher layer signal, such as radio resourcecontrol (RRC). The parameter that are given as the higher layer signalmay, for example, correspond to a cycle period and offset value of thesubframe.

After recognizing the SPS transmission/reception through the RRCsignaling, when the UE receives an activation or release signal of theSPS transmission through the physical downlink control channel(PDCCH)/enhanced PDCCH (EPDCCH), the UE performs or releases the SPStransmission/reception. More specifically, even if the SPS is assignedthrough the RRC signaling, instead of immediately performing the SPStransmission/reception, in case the activation or release signal isreceived through the PDCCH/EPDCCH, the UE performs the SPStransmission/reception in a subframe corresponding to a subframe cycleperiod and offset value that are assigned to the corresponding subframethrough the RRC signaling after applying modulation and a coding rate inaccordance with a frequency resource (resource block) and modulation andcoding scheme (MCS) information respective to the resource blockassignment that is designated by the corresponding PDCCH/EPDCCH.

(WAN (VoIP(/UL)) communication related) SPS activation/releaseoperations will hereinafter be described in more detail.

The UE may validate a semi-persistent scheduling activated PDCCH onlywhen the following conditions are satisfied.

1) CRC parity bits that are acquired for the PDCCH payload should bescrambled by a semi-persistent scheduling C-RNTI, and 2) a ‘new dataindicator’ field should be set to ‘0’.

The UE may validate a semi-persistent scheduling activated EPDCCH onlywhen the following conditions are satisfied.

1) CRC parity bits that are acquired for the EPDCCH payload should bescrambled by a semi-persistent scheduling C-RNTI, and 2) a ‘new dataindicator’ field should be set to ‘0’.

The UE may validate a semi-persistent scheduling activated MPDCCH onlywhen the following conditions are satisfied.

1) CRC parity bits that are acquired for the MPDCCH payload should bescrambled by a semi-persistent scheduling C-RNTI, and 2) a ‘new dataindicator’ field should be set to ‘0’.

The above-described validation is carried out in a case where all fieldsof the corresponding DCI format are configured as shown below in thefollowing table. Once the validation is achieved, the UE may considerthe received DCI information as valid semi-persistentactivation/release. If the validation is not achieved, the received DCIformat may be viewed to have been received with a non-matching CRC.

TABLE 1 DCI format DCI format DCI format 0 1/1A 2/2A/2B/2C/2D TPCcommand for scheduled set to ‘00’ N/A N/A PUSCH Cyclic shift DM RS setto ‘000’ N/A N/A Modulation and coding MSB is set N/A N/A scheme to ‘0’and redundancy version HARQ process number N/A FDD: set to FDD: set to‘000’ ‘000’ TDD: set to ‘0000’ TDD: set to ‘0000’ Modulation and codingN/A MSB is set to For the enabled transport scheme ‘0’ block: MSB is setto ‘0’ Redundancy version N/A set to ‘00’ For the enabled transportblock: set to ‘00’

Table 1 presented above shows an example of specific fields for SPSactivated PDCCH/EPDCCH validation.

TABLE 2 DCI format 0 DCI format 1A TPC command for scheduled PUSCH setto ‘00’ N/A Cyclic shift DM RS set to ‘000’ N/A Modulation and codingscheme set to ‘11111’ N/A and redundancy version Resource blockassignment and Set to all ‘1’s N/A hopping resource allocation HARQprocess number N/A FDD: set to ‘000’ TDD: set to ‘0000’ Modulation andcoding scheme N/A set to ‘11111’ Redundancy version N/A set to ‘00’Resource block assignment N/A Set to all ‘1’s

Table 2 presented above shows an example of specific fields for SPSreleased PDCCH/EPDCCH validation.

TABLE 3 DCI format 6- DCI format 6- 0A 1A HARQ process number set to‘000’ FDD: set to ‘000’ TDD: set to ‘0000 Redundancy version set to ‘00’set to ‘00’ TPC command for scheduled set to ‘00’ N/A PUSCH TPC commandfor scheduled N/A set to ‘00’ PUCCH

Table 3 presented above shows an example of specific fields for SPSactivated MPDCCH validation.

TABLE 4 Value of ‘TPC command for PUCCH’ n_(PUCCH) ^((1,p)) ‘00’ Thefirst PUCCH resource value configured by the higher layers ‘01’ Thesecond PUCCH resource value configured by the higher layers ‘10’ Thethird PUCCH resource value configured by the higher layers ‘11’ Thefourth PUCCH resource value configured by the higher layers

Table 4 presented above shows an example of specific fields for SPSreleased MPDCCH validation.

In case the DCI format indicates a downlink SPS activation, the TPCfield for PUCCH may be used to indicate one PUCCH resource value, amongthe 4 PUCCH resource values configured by the higher layers. At thispoint, mapping may be defined as shown below in the following table.

TABLE 5 Value of ‘TPC command for PUCCH’ n_(PUCCH) ^((1,p)) ‘00’ Thefirst PUCCH resource value configured by the higher layers ‘01’ Thesecond PUCCH resource value configured by the higher layers ‘10’ Thethird PUCCH resource value configured by the higher layers ‘11’ Thefourth PUCCH resource value configured by the higher layers

In a case where a plurality of sidelink (SL) and/or uplink (UL)semi-persistent scheduling (SPS) processes/configurations are configured(e.g., multiple SPS configurations(/processes) for uplink (and/oruplink+sidelink), e.g., SPS configuration/process for a Voice overinternet protocol (VoIP), SPS configuration/process for an intelligenttransport system (ITS)), the proposed methods that will hereinafter bedescribed in detail propose methods for efficiently managing andoperating such processes (e.g., SPS process(/configuration)activation/release, frequency resource re-assignment, HARQre-transmission).

For example, the terms ‘sidelink SPS process(/configuration)’ and‘uplink SPS process(/configuration)’ may each be interpreted as an SPSprocess(/configuration) for supporting ‘PC5 link based V2X messagetransmission’ and an SPS process(/configuration) for supporting ‘UU linkbased V2X message transmission (and/or the existing ‘WAN uplink(/VOIP)’SPS process(/configuration)).

[Proposed Method #1] By configuring(/signaling) (part of) a different(new) ‘V2X_SPS-RNTI’ per ‘sidelink and/or uplink SPSprocess(/configuration)’, independent management and operation (e.g.,SPS process(/configuration) activation/release, frequency resourcere-assignment, HARQ re-transmission) may be achieved for each ‘sidelinkand/or uplink process(/configuration)’.

For example, in case the corresponding rule is applied, this may beinterpreted as (part of) different ‘RNTI’ values beingconfigured(/signaled) between a plurality of sidelink SPSprocesses(/configurations) (or uplink SPS processes(/configurations))and/or as (part of) different ‘RNTI’ values being configured(/signaled)between a sidelink SPS process(/configuration) and an uplink SPSprocess(/configuration).

Herein, as another example, (part of) different (or common) ‘RNTI’values may also be configured(/signaled) between the existing (orconventional) WAN (VOIP(/uplink)) communication related SPSprocess(/configuration) (e.g., ‘SPS C-RNTI’) and the (V2X) uplink SPSprocess(/configuration) (and/or sidelink SPS process(/configuration)).This will hereinafter be described in more detail with reference to FIG.8 to FIG. 10.

FIG. 8 shows an example of an existing uplink SPS process.

Referring to FIG. 8, the base station transmits a higher layer signalincluding an SPS cycle period, e.g., a radio resource control (RRC)signal to the UE (S801).

The base station may transmit, for example, an uplink SPS activation DCIfor VoIP (this may be referred to as a VoIP UL SPS activation DCI) tothe UE (S802). The VoIP UL SPS activation DCI may include a cyclicredundancy check (CRC), and the CRC may be scrambled by using anSPS-C-RNTI (hereinafter referred to as a first RNTI).

The UE transmits a signal to the base station at an SPS cycle period byusing a resource according to the configuration of a VoIP UL SPSactivation DCI (S803).

The UE receives a DCI that releases the VoIP UL SPS (this may bereferred to as a VoIP UL SPS release DCI) (S804). The VoIP UL SPSrelease DCI may also include a CRC, and the CRC may be scrambled byusing an SPS-C-RNTI (a first RNTI).

The VoIP UL SPS activation DCI/VoIP UL SPS release DCI may be receivedthrough a physical downlink control channel (PDCCH) or an enhanced PDCCH(EPDCCH).

FIG. 9 shows an example of a case where an uplink SPS process is appliedto the V2X. Herein, the corresponding uplink SPS process will bereferred to as a V2X uplink SPS process.

Referring to FIG. 9, the base station transmits a higher layer signalincluding an SPS cycle period, e.g., a radio resource control (RRC)signal to the UE (S901).

The base station may transmit, for example, an uplink SPS activation DCIfor V2X (this may be referred to as a V2X UL SPS activation DCI) to theUE (S902). The V2X UL SPS activation DCI may include a cyclic redundancycheck (CRC), and the CRC may be scrambled by using a V2X-SPS-RNTI(hereinafter referred to as a second RNTI). Herein, the second RNTI maya correspond to another RNTI that is differentiated from theabove-described first RNTI.

The UE transmits a V2X signal to the base station at an SPS cycle periodby using a resource according to the configuration of a V2X UL SPSactivation DCI (S903).

The UE receives a DCI that releases the V2X UL SPS (this may be referredto as a V2X UL SPS release DCI) (S904). The V2X UL SPS release DCI mayalso include a CRC, and the CRC may be scrambled by using a V2X-SPS-RNTI(a second RNTI).

FIG. 10 shows a UE operation method according to uplink SPS.

Referring to FIG. 10, the UE receives a DCI instructing an uplink SPSactivation or release (S210). The UE decodes the DCI based on a firstRNTI or a second RNTI (S220). The first RNTI and the second RNTI havealready been described in detail, respectively, with reference to FIG. 8and FIG. 9. FIG. 8 to FIG. 10 may correspond to application examples ofthe [Proposed Method #1].

[Proposed Method #2] A (single) common (or shared) ‘V2X_SPS-RNTI’ isconfigured(/signaled) to a plurality of ‘sidelink (and/or uplink) SPSprocesses(/configurations), and this method may identify (ordistinguish) to which ‘sidelink (and/or uplink) SPSprocess(/configuration)’ the corresponding control information isrelated through a (new) pre-defined(/signaled) specific field within a‘(sidelink (and/or uplink)-SPS) (activation/release) DCI’ that isdecoded by using the corresponding RNTI (e.g., a ‘sidelink (and/oruplink) SPS process(/configuration) index(/ID)’ field and/or a fieldannouncing an ‘LCID’ being linked(/interconnected) to a ‘sidelink(and/or uplink) SPS process(/configuration) index(/ID)’ (that isconfigured(/signaled) through a pre-defined signaling)).

As field(s) being used for the above-described purpose, a ‘DM-RS CS (3bit) field’ (e.g., a case where a VVOIP) uplink (and/or sidelink)-SPS)(activation/release) DCI’ of the (existing) ‘DCI format 0’ type is(re-)used (for the purpose of a ‘(sidelink (and/or (V2X) uplink)-SPS)(activation/release) DCI’)) and/or a ‘HARQ ID (3/4 bit)/RV (2 bit)field’ (e.g., a case where a AVOIP) uplink(/downlink) (and/orsidelink)-SPS) (activation/release) DCI’ of the (existing) ‘DCI format1/1A/2/2A/2B/2C/2D’ type is (re-)used (for the purpose of a VV2X)sidelink (and/or uplink)-SPS) (activation/release) DCI’)) may be(re-)used.

Herein, for example, a size (X_size) of the field being used for thecorresponding purpose may be fixed to a pre-configured(/signaled) value(e.g., ‘3 bit’), and, in case a (maximum) number of ‘sidelink (and/oruplink) SPS processes(/configurations)’ (SPS NUM) beingconfigured(/signaled) (in the form of a ‘carrier(kell)-specificconfiguration’) from a network (or (serving) cell) can be varied (orchanged), ‘(X_size−ceiling(LOG2(SPS NUM)))’ (and/or‘(X_size−floor(LOG2(SPS NUM)))) bits (herein, for example, the‘ceiling(X)’ and the ‘floor(X)’ may respectively indicate a functiondrawing a ‘minimum integer value that is greater than or equal to X’ anda function drawing a ‘maximum integer value that is smaller than orequal to X’) may be processed with zero (or a specificpre-configured(/signaled) value) padding (e.g., this may be used for thepurpose of a ‘virtual CRC’).

Herein, for example, in case a common ‘RNTI’ value isconfigured(/signaled) between an existing WAN (VOIP(/uplink))communication related SPS process(/configuration) and a (V2X) uplink SPSprocess(/configuration) (and/or in case a(/an) ‘(activation/release)DCI’ having the same (payload) size is used), it may be distinguished towhich one of the existing WAN (VOIP(/uplink)) communication related SPSprocess(/configuration) and the (V2X) uplink SPS process(/configuration)the corresponding control information is related through (a re-usage of)(A) a pre-defined(/signaled) new field (e.g., ‘1 bit’) and/or (B) apre-designated(/signaled) existing field within the‘(activation/release) DCI’ being decoded by using the correspondingcommon RNTI (this will hereinafter be referred to as C_V2XARDCI) (forexample, in case the ‘(activation/release) DCI’ of the (existing) ‘DCIformat 0’ type is (re-)used, an ‘MCS/RV (5 bits) field (MSB (1 bit))’and/or a ‘TPC (2 bits) field (MSB (1 bit))’ and/or a ‘CS DM RS (3 bits)field (MSB (1 bit))’ may be (re-)used).

Herein, for example, by defining a new field in the C_V2XARDCI, in casethe (payload) size becomes larger than the ‘(activation/release) DCI’that is related to the existing WAN (VOIP(/uplink)) communication (thatis transmitted within the same user equipment (UE) specific search space(USS)(/common search space (CSS))), in order to prevent an increase inthe number of blind decoding sessions of the UE, zero (or a specificpre-configured(/signaled) value) padding may be performed (e.g., thismay be used for the purpose of a ‘virtual CRC’) until the WANARDCI(payload) size becomes identical to the (payload) size of theC_V2XARDCI.

FIG. 11 is a diagram showing a comparison between the existing (VoIP)uplink SPS activation/release DCI (first DCI) and the V2X uplink SPSactivation/release DCI (second DCI) by applying the [Proposed Method#2]. As respectively described above with reference to FIG. 8 and FIG.9, the first DCI may be CRC-scrambled by the SPS-C-RNTI (first RNTI),and the second DCI may be CRC-scrambled by the V2X-SPS-RNTI (secondRNTI).

Referring to FIG. 11, each of the first DCI and the second DCI includesa plurality of fields. The first DCI and the second DCI may include aplurality of common fields and a plurality of fields that aredifferentiated from one another. For example, the first DCI and thesecond DCI may commonly have a carrier indication field (0 bit or 3bits), a resource block assignment and hopping resource assignmentfield, an MCS and redundancy version (RV) field, and so on. Conversely,the first DCI may include a cyclic shift (CS) field corresponding to ademodulation reference signal (DM-RS) (this will hereinafter be referredto as a DM-RS CS field), whereas the second DCI may include an uplinkSPS configuration index field instead of the DM-RS CS field.

In light of the RNTI, if the DCI is CRC-scrambled by the V2X-SPS-RNTI(second RNTI), it may be expressed that the DM-RS CS field (this refersto the above-described CS DM RS (3 bits) field) does not exist and thatthe uplink SPS configuration index field exists. Alternatively, it mayalso be expressed that, in the first DCI, the DM-RS CS field is used forits initial purpose, which corresponds to announcing (or notifying) thecyclic shift of the DM-RS, and that, in the second DCI, the DM-RS CSfield is used as an uplink SPS configuration index field.

FIG. 12 shows an example of a method for interpreting a specific fieldwhen decoding the first DCI and the second DCI.

Referring to FIG. 12, the UE receives a DCI indicating uplink SPSactivation or release (S310), and, then, in case the DCI is decodedbased on a second RNTI, a DM-RS cyclic shift field of the DCI isinterpreted as a UL SPS configuration index (S320).

As described above in [Proposed Method #2] and FIG. 11, in the V2Xuplink SPS activation/release DCI (second DCI), the DM-RS cyclic shiftfield included in the existing uplink SPS activation/release DCI (firstDCI) may be interpreted as a UL SPS configuration index. As describedabove, this may also be expressed as the UL SPS configuration indexfield being included in the V2X uplink SPS activation/release DCI(second DCI) instead of the DM-RS cyclic shift field.

Hereinafter, a DCI scheduling a physical sidelink control channel(PSCCH) or a physical sidelink shared channel (PSSCH) will be describedin detail. The DCI scheduling the sidelink channel(s) may include adynamic DCI (e.g., a method of scheduling only one transmission (byusing only one DCI)) and a SPS method-based DCI (e.g., a method ofscheduling a plurality of transmission (by using only one DCI), and,more specifically, a DCI activation/release a sidelink SPS).

FIG. 13 is a diagram showing a comparison between a DCI for dynamicallyscheduling a sidelink channel (DCI for Dynamic scheduling (V2X SLdynamic DCI)) and a sidelink channel SPS activation/release DCI (V2X SLSPS activation/release DCI).

The total bit sizes of each of the V2X SL dynamic DCI and the V2X SL SPSactivation/release DCI may be differently configured. The V2X SL dynamicDCI and the V2X SL SPS activation/release DCI may include a commonfield, and the V2X SL SPS activation/release DCI may further includeadditional fields. More specifically, the V2X SL SPS activation/releaseDCI may have a larger total bit size.

For example, the V2X SL dynamic DCI and the V2X SL SPSactivation/release DCI may commonly include a carrier indication field(3 bits), a field indicating a lowest index of a sub-channel for asub-channel assignment for an initial transmission, a field indicating afrequency resource position, a field indicating a time gap between aninitial transmission and a re-transmission, and so on.

In comparison with the V2X SL dynamic DCI, the V2X SL SPSactivation/release DCI may further include a sidelink SPS configurationindex (3 bits) and a sidelink SPS activation/release field (1 bit).

FIG. 14 shows an example of a method for transmitting downlink controlinformation for sidelink scheduling according to another exemplaryembodiment of the present invention.

Referring to FIG. 14, a wireless device generates a DCI instructing aV2X sidelink SPS activation or release (S410), and, then, the wirelessdevice transmits the DCI (S420).

At this point, the DCI may further include a sidelink SPS configurationindex (3 bits) and a V2X sidelink SPS activation/release field (1 bit),which are not included in the V2X sidelink dynamic DCI. Morespecifically, the V2X sidelink SPS activation/release DCI may have alarger total bit size as compared to the V2X sidelink dynamic DCI.

The sidelink SPS configuration index field may include informationindicating at least one the plurality of sidelink SPS configurations.

[Proposed Method #3] (For example, in case a (single) common‘V2X_SPS-RNTI’ and ‘(activation/release) DCI format’ are used for themanagement and operation of a plurality of ‘sidelink and/or uplink SPSprocess(/configuration)’) a subframe (SF) set(/cell set) (and/or asearch space (SS) type (CSS/USS) and/or a control channel (PDCCH/EPDCCHset) type) in which the related ‘(sidelink and/or uplink-SPS)(activation/release) DCI’ is received for each ‘sidelink and/or uplinkSPS process(/configuration)’ may be differently (or independently)configured(/signaled).

For example, such operation may also be (limitedly) applied only in asituation where a plurality of sidelink and/or uplink SPS transmissionsare not performed in one subframe.

In case (part of) the above-described proposed methods (e.g., [ProposedMethod #1], [Proposed Method #2], [Proposed Method #3]) are applied, (A)a differentiation (related to SPS process(/configuration)activation/release, frequency resource re-assignment, HARQre-transmission operation(/instruction)) may be performed between aplurality of ‘sidelink SPS process(/configuration)’ (or ‘uplink SPSprocess(/configuration)’) and/or (B) a differentiation (related to SPSprocess(/configuration) activation/release, frequency resourcere-assignment, HARQ re-transmission operation(/instruction)) may beperformed between a ‘sidelink SPS process(/configuration)’ and an‘uplink SPS process(/configuration)’.

For example, a (single) common ‘V2X_SPS-RNTI’ may beconfigured(/signaled) to a plurality of ‘sidelink and/or uplink SPSprocesses(/configurations)’, and an ‘activation/release’(/frequencyresource re-assignment/HARQ re-transmission) instruction that is relatedto a plurality of ‘sidelink and/or uplink SPSprocesses(/configurations)’ may be performed at the same time throughone or more (new) pre-defined(/signaled) specific fields within a‘(sidelink and/or uplink-SPS) (activation/release) DCI’, which isdecoded by the corresponding RNTI.

For example, (A) in case the (new) specific field(s) can be implementedin the form of a bitmap (e.g., in case (a maximum of) ‘4’ ‘sidelinkand/or uplink SPS processes(/configurations)’ can be processed with‘activation/release’(/frequency resource re-assignment/HARQre-transmission) at the same time), the corresponding field may beimplemented in the form of a bitmap having a length of ‘4 bits’(‘WXYZ’).

For example, in the bitmap each of W, X, Y, and Z corresponds to one biteach being given a value of 0 or 1. In each bit, 0/1 may respectivelyindicate the activation/release of the corresponding sidelink and/oruplink SPS process(/configuration). For example, W may instruct a‘sidelink and/or uplink SPS process(/configuration) #0activation/release’. X may instruct a ‘sidelink and/or uplink SPSprocess(/configuration) #1 activation/release’. Y may instruct a‘sidelink and/or uplink SPS process(/configuration) #2activation/release’. And, Z may instruct a ‘sidelink and/or uplink SPSprocess(/configuration) #3 activation/release’. This may also beunderstood as the ‘sidelink and/or uplink SPS process(/configuration)index(/ID)’ (information) that is linked with(/interconnected to) aspecific field value being pre-configured(/signaled) in advance.

Alternatively, (B) the (new) specific field(s) may be implemented in thesame number of fields as the (maximum) number of ‘sidelink and/or uplinkSPS processes(/configurations)’ that can be processed with‘activation/release’(/frequency resource re-assignment/HARQre-transmission) at the same time. For example, in case (a maximum of)‘4’ ‘sidelink and/or uplink SPS processes(/configurations)’ may be‘activated/released’ at the same time, and, in case the ‘sidelink and/oruplink SPS process(/configuration) index(/ID)’ is expressed as ‘3 bits’,the corresponding field(s) may be implemented as ‘4’ fields each havingthe length of ‘3 bits’.

(According to the proposed method, in case‘activation’(/release/frequency resource re-assignment/HARQre-transmission) related to a plurality of ‘sidelink and/or uplink SPSprocesses(/configurations)’ are indicated (or instructed) at the sametime, in order to reduce collision between ‘sidelink and/or uplink SPSprocesses(/configurations)’ having the same ‘cycle period value’ and/or‘frequency(/time) resource position value’, among the corresponding‘sidelink and/or uplink SPS processes(/configurations)’ (that aresimultaneously instructed (or indicated)),) the ‘subframe offset’information per ‘sidelink and/or uplink SPS process(/configuration)’ maybe configured through a ‘subframe offset’ information field per‘sidelink and/or uplink SPS processes(/configurations)’ being (newly)defined within (A) a ‘higher layer signaling (e.g., ‘RRC’)’ or (B) a‘(sidelink and/or uplink-SPS) (activation/release) DCI’.

Herein, for example, ‘subframe gap (SF gap)’ information being appliedbetween a plurality of ‘sidelink and/or uplink SPSprocesses(/configurations)’ (that are indicated at the same time) may beconfigured(/signaled) (e.g., in case ‘2’ ‘sidelink and/or uplink SPSprocesses(/configurations)’ having the same ‘cycle period value (P)’ and‘frequency(/time) resource position value’ are ‘activated’ at the sametime, (according to an increasing order (or a decreasing order) of the‘sidelink and/or uplink SPS process(/configuration) index(/ID)’) a(periodic) resource related to ‘sidelink and/or uplink SPSprocess(/configuration) #1’ may be indicated in ‘SF#0, SF#P, . . . ,SF#(N·P)’ (or ‘SF#(0+SF GAP), SF#(P+SF GAP), . . . , SF#(N·P+SF GAP)’),and a (periodic) resource related to ‘sidelink and/or uplink SPSprocess(/configuration) #2’ may be indicated in ‘SF#(0+SF GAP), SF#(P+SFGAP), . . . , SF#(N·P+SF GAP)’ (or in ‘SF#0, SF#P, . . . , SF#(N·P)’)).Herein, SF indicates a subframe.

Herein, as an additional example, the ‘sidelink and/or uplink SPSprocess(/configuration)’ that is processed with‘activation’(/release/frequency resource re-assignment/HARQre-transmission) may be limited to those having different ‘cycle periodvalues’ and/or ‘frequency(/time) resource position values’.

For example, (A) (according to the above-described proposed method) incase ‘sidelink and/or uplink SPS processes(/configurations)’ having thesame ‘cycle period value’ and/or ‘frequency(/time) resource positionvalue’ are processed with ‘activation’(/release/frequency resourcere-assignment/HARQ re-transmission) at the same time and/or (B) in casea plurality of ‘sidelink and/or uplink SPS processes(/configurations)’having (partially) different ‘resource block sizes/positions’ and/or‘cycle period values’ and/or ‘MCS values’, and so on, areconfigured(/signaled), which ‘sidelink and/or uplink SPSprocess(/configuration)’ is valid within the current subframe (set) maybe announced (or notified) through a pre-defined (higher layer/physicallayer) signaling (e.g., a ‘(sidelink and/or uplink-SPS)(activation/release) DCI’).

A (partially) different parameter (set) (e.g., ‘resource blocksize/position’, ‘MCS value’) may be mapped(/signaled) perpre-configured(/signaled) subframe set, and the corresponding parameter(set) may be applied to the ‘sidelink and/or uplink SPSprocess(/configuration)’ that is valid(/‘on’) (or being used) within aspecific subframe set.

Alternatively, (unlike the above-described proposed method) in case the‘sidelink and/or uplink SPS process(configuration) index(/ID)’ field(s)is/are not defined within the ‘(sidelink and/or uplink-SPS)(activation/release) DCI’ and a periodic resource related to ‘sidelinkand/or uplink SPS process(/configuration) #X’ is indicated at a timepoint of ‘SF#N’, the ‘(sidelink and/or uplink-SPS) release(/frequencyresource re-assigning/HARQ re-transmitting) DCI’, which is received at atime point of ‘SF#(N−K)’ (e.g., ‘K=4’), may be viewed(/assumed) as a DCI(implicitly) indicating a ‘release(/frequency resourcere-assignment/HARQ re-transmission)’ of the corresponding ‘sidelinkand/or uplink SPS process(/configuration) #X’.

For example, (A) the ‘Mode 1 DCI’ (e.g., V2X SL (and/or uplink) SPSactivation/release DCI) announcing (or notifying) (PSCCH and/or PSSCH)scheduling information related to sidelink (and/or uplink) SPS may beconfigured of (part of) the following fields. And/Or, (B) ‘K’ number of(repeated) re-transmission operations related to the same transmissionblock (TB) may be defined to be performed in accordance with (part of)the following rules.

The decoding of ‘Mode 1 DCI’ may be attempted to be performed by usingan (additionally configured(/signaled)) ‘RNTI’ that is different from(or the same as) the (above-described) ‘(sidelink and/or uplink-SPS)(activation/release) DCI’.

(Part of) The field(s) within the ‘Mode 1 DCI’ (e.g., at least one of(Example #1-1), (Example #1-2), (Example #1-3), (Example #1-5), and(Example #1-6), which will be described below) may bere-configured(/used) as a field(/fields) of ‘schedulingassignment(/PSCCH)’.

Types of fields configuring the ‘Mode 1 DCI’

EXAMPLE #1-1

A ‘sidelink and/or uplink SPS process(/configuration) index(/ID)’ field.

EXAMPLE #1-2

A ‘timing gap’ (indication) field between ‘data(/PSSCH)’ beinginterconnected to the ‘scheduling assignment(/PSCCH)’ (and/or aninterval (indication)) field between a ‘resource (re-)selectiontriggering timing’ and a ‘scheduling assignment(/PSCCH) transmissiontiming’). Herein, for example, when being operated in ‘Mode 1’, thecorresponding field value may be fixed to a pre-defined(/signaled)specific value (e.g., ‘timing gap=0’), and, in this case, thecorresponding filed may also be omitted.

EXAMPLE #1-3

A ‘re-transmission number counter(/indicator) (related to the sametransmission block (TB))’ field (and/or ‘a redundancy version (RV)(related to the same TB)’ field). Herein, for example, the correspondingfield may, most particularly, be useful (only) when the ‘Mode 1 DCI’(and/or ‘SA(/PSCCH)’) is(/are) transmitted along with one another (orcollectively) during each re-transmission related to the same TB.

EXAMPLE #1-4

A ‘SA(/PSCCH)’ related frequency(/time) resource information field.

EXAMPLE #1-5

A ‘data(/PSSCH)’ related frequency(/time) resource information field.

EXAMPLE #1-6

A ‘SA(/PSCCH)’ and/or ‘data(/PSSCH)’ related ‘transmit power control(TPC) command’ field (e.g., in case a size of the corresponding ‘TPCcommand’ field is equal to ‘1 bit’, a ‘0’ value may indicate an‘application of a pre-configured(/signaled) (maximum) transmission powervalue (i.e., ‘no open-loop power control’)’, and a ‘1’ value mayindicate a ‘determination of the transmission power value according to apre-defined ‘open-loop power control’ equation) and/or a fieldannouncing (or notifying) whether or not a ‘data(/PSSCH)’ related‘frequency hopping’ is applied and/or a ‘data(/PSSCH)’ related ‘timeresource pattern (T-RPT)’ field.

EXAMPLE #1-7

An indicator field related to a ‘sidelink and/or uplink SPSprocess(/configuration) activation(/release)’.

EXAMPLE #1-8

An information field related to a time period having a pre-determinedlength(/size) (e.g., ‘subframe’ unit) during which a resource related toa ‘sidelink and/or uplink SPS process(/configuration)’ is maintained (oran information field indicating a number of ‘sidelink and/or uplink SPSprocess(/configuration)’ cycle periods during which the correspondingresource is maintained). This field may be interpreted as a type of‘activation duration timer’ information.

In case the above-described ‘Mode 1 DCI’ is received, a rule of ‘K’number of (repeated) re-transmission operations that is related to thesame transmission block (TB) may be determined by at least one of thefollowing examples.

EXAMPLE #2-1

In case the ‘Mode 1 DCI’ (and/or ‘SA(/PSCCH)’) is(/are) transmittedalong with one another (or collectively) during eachre-transmission(/initial transmission) related to the same TB, there-transmission(/initial transmission) may be performed in accordancewith the (‘SA(/PSCCH)’ and/or ‘data(/PSSCH)’) scheduling informationthat is announced(/indicated) by the above-described fields within thecorresponding ‘Mode 1 DCI’ (e.g., (Example #1-1)(4 Example #1-2)),(Example #1-3), (Example #1-4), (Example #1-5), and so on).

EXAMPLE #2-2

In order to perform ‘K’ number of (repeated) re-transmissions related tothe same TB, in case only one ‘Mode 1 DCI’ (and/or ‘SA(/PSCCH)’) relatedto the initial transmission scheduling is transmitted, (A) it may beassumed that the (‘data(/PSSCH)’) re-transmission is performed withinconsecutive subframes by using the same frequency resource as theinitial transmission or (B) time resource pattern (T-RPT) informationbeing related to the (‘data(/PSSCH)’) re-transmission(/initialtransmission) may be announced (or notified) within (one) ‘Mode 1 DCI’(and/or ‘SA(/PSCCH)’) related to the initial transmission scheduling.For example, in case of (B), it may be assumed that the re-transmissionrelated frequency resource is identical to the frequency resource of theinitial transmission.

FIG. 15 shows an example of a method for performing an SPS processaccording to yet another exemplary embodiment of the present invention.

Referring to FIG. 15, the wireless device determines a priority levelcorresponding to each of a plurality of SPS processes (S510), and a SPSrelated parameter may be differently configured in accordance with thepriority level of each SPS process (S520). The SPS processes maycorrespond to SPS processes(/configurations) corresponding to a sidelinkand/or SPS processes(/configurations) corresponding to an uplink. TheSPS related parameter may, for example, include at least one of a firstinformation announcing a timing gap between a sidelink controlinformation and data being scheduled by the sidelink controlinformation, a second information announcing a timing gap between a timepoint when a resource selection is triggered and the sidelink controlinformation, a third information announcing a sensing window size, whichcorresponds to a section during which sensing is to be performed for theresource selection, and a fourth information related to an open-looptransmission power.

More specifically, in case a plurality of ‘sidelink and/or uplink SPSprocesses(/configurations)’ are configured(/signaled), for example,‘timing gap’ values between the ‘data(/PSSCH)’ being interconnected tothe ‘SA(/PSCCH)’ per ‘sidelink and/or uplink SPS process(/configuration)(set)’ (and/or an interval (or gap) between a ‘resource (re-)selectiontriggering timing’ and a ‘SA(/PSCCH) transmission timing’ and/or a‘sensing window size (that is based on SA decoding/energy measurement)’and/or an ‘(open-loop) transmission power parameter’) may be differentlyconfigured(/signaled). Accordingly, parameter levels between the‘sidelink and/or uplink SPS processes(/configurations) (set)’ may be(implicitly) designated differently.

For example, by configuring(/signaling) a ‘timing gap’ having arelatively large value (or small value) (and/or an interval (or gap)between a ‘resource (re-)selection triggering timing’ and a ‘SA(/PSCCH)transmission timing’ and/or a ‘(SA decoding/energy measurement based)sensing window size’) within a ‘sidelink and/or uplink SPSprocess(/configuration) (set)’ having a relatively high priority level,a V2X UE performing V2X communication through theconfiguration(/signaling) of a ‘sidelink and/or uplink SPSprocess(/configuration) (set)’ having a relatively low priority level(i.e., a ‘timing gap’ having a relatively small value (or large value)(and/or an interval (or gap) between a ‘resource (re-)selectiontriggering timing’ and a ‘SA(/PSCCH) transmission timing’ and/or a ‘(SAdecoding/energy measurement based) sensing window size’) may be capableof detecting(/sensing) a ‘SA(/PSCCH)’ having a relatively high prioritylevel (at a high probability) and may also be capable ofselecting(/scheduling) its own ‘data(/PSSCH)’ resource while avoiding(as much as possible) the ‘data(/PSSCH)’ being scheduled by thecorresponding ‘SA(/PSCCH)’.

The ‘(open-loop) transmission power parameter(s)’ having a relativelyhigh value (e.g., ‘P_O’ and/or ‘ALPHA’, and so on) having a relativelylarge value may be configured(/signaled) within a ‘sidelink and/oruplink SPS process(/configuration) (set)’ having a relatively highpriority level. Herein, for example, the ‘sidelink and/or uplink SPSprocess(/configuration) (set)’ having a relatively high priority levelmay be used(/assigned) for an ‘event-triggered V2X messagetransmission(/service type)’ and/or a ‘service type requiring arelatively high ‘reliability’.

More specifically, the first information, the second information, andthe third information corresponding to an SPS process having arelatively high priority level, among a plurality of SPS processes, maybe configured to have larger values (or smaller values) than the firstinformation, the second information, and the third informationcorresponding to an SPS process having a relatively low priority level.

Additionally, among the plurality of SPS processes, the fourthinformation corresponding to the SPS process having a relatively highpriority level may be configured to have a larger value (or a smallervalue) than the fourth information corresponding to the SPS processhaving a relatively low priority level.

Among the plurality of SPS processes, the SPS process having therelatively high priority level may be used for a vehicle-to-everything(V2X) message transmission that is triggered by an event.

Among the plurality of SPS processes, the SPS process having therelatively high priority level may be used for a service type requiringa relatively high reliability.

In case a pre-defined event occurs (e.g., in case a speed/traveldirection/position variation (or change), and so on, equal to or greaterthan a pre-defined(/signaled) threshold value (as compared to a previoustime point at which a ‘V2X message transmission’ has been performed)occurs, a ‘V2X message (e.g., ‘CAM’) generation(/transmission)’ may be(immediately) triggered. Accordingly, a ‘V2X messagegeneration(/transmission)’ related ‘cycle period’ and/or ‘size variationpattern’ (and/or an interval between consecutive ‘V2X messagegenerations(/transmissions)’), and so on, may be changed (or varied)(within the time domain).

When considering such problem(/phenomenon), it may be difficult for theV2X UE to perform ‘V2X message transmission’ of high ‘reliability’(and/or satisfying the ‘latency requirement’) through a specific cycleperiod and/or a time/frequency resource size and/or MCS of a ‘single SPSconfiguration/process’, which is/are configured(/signaled) by the basestation. In order to resolve this problem, the cycle period related tothe ‘single SPS configuration(/process)’ may be configured to be(extremely) short and a large size of the (time/frequency) resource maybe assigned. However, in the aspect of efficient resource management,this method is not preferable.

As a solution, the base station may configure(/signal) ‘multiple SPSconfigurations(/processes)’ (having different cycle periods and/or(time/frequency) resource sizes (and/or MCS)) to the V2X UE and, then,may also allow the V2X UE to report (part of) the following information.

The information report may be performed through a pre-defined(/signaled)channel (e.g., ‘PUSCH(/PUCCH)’, ‘SR’). The base station that hasreceived(/been reported of) such information may‘release’(/‘de-activate’) the ‘SPS configuration(/process)’ that is notused by the corresponding V2X UE (or (most) inappropriate to thecorresponding V2X UE), or the corresponding base station may newlyconfigure(/signal) a (most) appropriate ‘SPS configuration(/process)’ tothe corresponding V2X UE (or the cycle period and/or (time/frequency)resource size (and/or MCS) related to the (existing) ‘SPSconfiguration(/process)’).

As another example, the base station that has received(/been reportedof) such information may (finally) instruct the corresponding V2X UE toperform switching to the (most) appropriate ‘SPSconfiguration(/process)’ among the ‘multiple SPSconfigurations(/processes)’.

Herein, for example, the corresponding switching instruction may beperformed through a pre-defined(/signaled) channel (e.g.,‘(E)PDCCH(/PDSCH)’). Herein, for example, this rule may be limitedlyapplied only to the ‘Mode 1 (i.e., a method according to which the basestation controls(/signals) the ‘V2X message transmission’ relatedscheduling information)’ based V2X communication and/or ‘RRC connectedV2X UE(/V2X UE within the cell coverage)’.

The V2X UE may report at least one of the information described below.

EXAMPLE #A

‘SPS configuration(/process) (index/ID) information’ that is used by thecorresponding V2X UE (or (most) appropriate to the corresponding V2X UE)(and/or that is not used by the corresponding V2X UE (or (most)inappropriate to the corresponding V2X UE), among theconfigured(/signaled) ‘multiple SPS configurations(/processes)’.

EXAMPLE #B

‘Utilization information’ and/or ‘collision (with another V2 UE)detection information’ and/or ‘interference(/energy) measurementinformation’ and/or ‘timing misalignment’ information between a timepoint(/cycle period) at which its (current) ‘V2X messagetransmission(/generation) is misaligned (e.g., this may also beinterpreted as ’(estimated) cycle period/offset information that isappropriate to the (current) ‘V2X message transmission(/generation)’time point(/cycle period) of the corresponding V2X UE) perconfigured(/signaled) ‘multiple SPS configurations(/processes)’.

As another example, a V2X UE being configured(/signaled) with ‘multipleSPS configurations(/processes)’ having different cycle periods and/or(time/frequency) resource sizes (and/or MCS) from the base station mayselect/use a ‘SPS configuration(/process)’ that is most appropriate tothe corresponding V2X UE, and the V2X UE may report the respectiveresult (e.g., ‘SPS configuration(/process) (index/ID) information’ thatis selected/used by the V2X UE) to the base station.

Hereinafter, a method for efficiently supporting V2X communicationrelated sidelink SPS operations and uplink SPS operations, e.g., amethod for configuring a DCI format field will be described in detail.

Firstly, sidelink SPS operations will be described in detail.

In case of Mode 1 SPS, the base station may configure a plurality of(multiple) SPS configurations to the UE. A SPS configuration specificMCS and a SPS configuration specific cycle period may be configured. Thebase station may trigger/release dynamically different SPSconfigurations by using the PDCCH/EPDCCH. Before a transmission timepoint that is associated to the SPS configuration, the UE may announceto the base station that the UE will not be performing datatransmission.

For V2V, Mode 1 may support cross carrier scheduling and dynamicscheduling for sidelink SPS.

The multiple SPS configuration will hereinafter be described in detail.

In a PC 5-based Mode 1 SPS, the base station may configure multiple SPSconfigurations. The parameters in each SPS configuration may bepre-determined (or determined in advance) by a higher layer signal. Forexample, an SPS offset may vary per SPS configuration, and an accuratemapping between an index of each SPS configuration and an SPS offsetvalue may be defined by an RRC signal.

The UE may request for a wanted SPS configuration, and the base stationmay activate the SPS configuration in accordance with the request madeby the UE. The configuration index of the SPS configuration may bedelivered through an SPS trigger message, and, accordingly, the wantedSPS configuration may be verified. If the UE is capable of managing andoperating only one SPS configuration at a time, the configuration indexof the SPS configuration may be converted to several bits. For example,if a total of 8 SPS configurations exist, a configuration index that isactivated or that is to be activated may be announced through 3 bits,and this may then be delivered through an SPS trigger message.

Conversely, if the UE is capable of managing and operating a pluralityof SPS configurations at the same time, indexes corresponding to theplurality of SPS configurations may be expressed in the form of abitmap. For example, if a total of 8 SPS configurations exist, aconfiguration index that is activated or that is to be activated may beannounced through a bitmap of 8 bits, and this may then be deliveredthrough an SPS trigger message.

After the triggering or release of a sidelink SPS configuration, if thebase station does not monitor a sidelink message, the base stationcannot confirm whether the UE has actually performed the SPS messagetransmission or whether the UE has suspended the transmission, and soon. Therefore, the UE may feedback an ACK/NACK corresponding to whetheror not the UE has correctly received sidelink SPS trigger/releasemessage.

<(E)PDCCH for Sidelink SPS>

The DCI for a sidelink SPS may be transmitted through a PDCCH or anEPDCCH. Such DCI may be referred to as DCI Format 5. DCI Format 5 mayinclude at least one of the following fields.

A resource indication field for the PSCCH. This field may be determinedto have a size of 6 bits.

A TPC command for the PSCCH and the PSSCH. This field may be determinedto have a size of 1 bit.

A frequency hopping flag (1 bit), a resource block assignment andhopping resource assignment field (depending upon the bandwidth, thisfield may be determined to have a size of any one of 5 bits to 13 bits).A time resource pattern (7 bits).

If a number of information bits included in DCI Format 5, which ismapped to a given search space, is smaller than a payload size of DCIFormat 0, which schedules the same serving cell, 0 (zero) values may beappended to DCI Format 5 so that the payload size can be the same as thepayload size of DCI Format 0 (zero padding). In this case, bits of theappended 0 (zero) values, i.e., the number of zero padding bits may beequal to 0 or may be equal to diverse values other than 0. Whenconsidering this characteristic, it is will not be preferable to use thezero padding bits as a new field. More specifically, in order to adopt anew field, such as an SPS configuration index, to a DCI format, part (orsome) of the existing fields may be required to be changed. Mostparticularly, this may correspond to a case where an existing DCI format(e.g., DCI Format 5) is re-used.

Considering the aspects of complexity in the detection (blind decoding)of an SPS configuration and saving (E)PDCCH resources, the 2 methodsdescribed below may be taken into consideration.

1) A method of using different RNTIs for each SPS configuration.According to this method, additional (or additionally appended) DCI bitsare not required.

2) A method of adopting an ‘SPS configuration index’ field while usingthe same RNTI.

In the method where the DCI bits are not increased, a specific RNTI maybe assigned to each SPS configuration. For example, different RNTIs,such as SL SPS C-RNTI 0, SL SPS C-RNTI 1, . . . , may be assigned to theSPS configuration. In this case, an excessively large number of RNTIsmay be needed, and the UE may be required to perform a large number ofblind decoding sessions in order to detect the SPS trigger/releasemessage. Therefore, it may be preferable to perform the method of 2)rather than the method 1). More specifically, it may be preferable thateach SPS configuration uses a common RNTI and that each SPSconfiguration includes a field indicating to which SPS configuration thetrigger/release corresponds.

The SPS configuration field may be expressed as an index of the SPSconfiguration. For example, in case 7 SPS configurations exist, the sizeof an SPS configuration field may be equal to 3 bits. The SPSconfiguration field may also be expressed in the form of a bitmap. Theexample presented above, the SPS configuration field may be expressed asa bitmap of 7 bits. In this case, a simultaneous management andoperation of the plurality of SPS configurations may be adequate forperforming indication (or instruction).

Hereinafter, cross carrier scheduling and dynamic scheduling forsidelink SPS for V2V in Mode 1 will be described in detail. It ispreferable that a(n) (E)PDCCH design for a sidelink SPS is compatible toa sidelink dynamic scheduling. One of the methods for achieving this isto include an indication field indicating whether the design is fordynamic scheduling or for SPS scheduling. A more resource-saving methodcorresponds to differentiating the scheduling mode by the SPSconfiguration field itself. For example, in case the value of the SPSconfiguration field is equal to ‘000’, this may indicate dynamicscheduling or a single transmission (e.g., one TB transmission). Othervalues may be respectively matched to SPS configuration 0 to SPSconfiguration 7.

In case of dynamic scheduling, after transmitting one transmission block(TB), sidelink resources that are assigned by the base station areautomatically released. Other operations may be the same as the sidelinkSPS operations. Which particular value (state) of the SPS configurationfield indicates the dynamic scheduling mode and/or the SPS schedulingmode may be signaled or pre-determined by the base station in advancethrough a higher layer signal (this may be determined in a standardspecification).

FIG. 16 describes an example of validating a DCI as a DCI format for V2Xsidelink SPS activation/release or as a V2X sidelink dynamic DCI.

A DCI format for V2X sidelink SPS activation/release and a V2X sidelinkdynamic DCI may include at least one or more common fields.Additionally, the DCI format for V2X sidelink SPS activation/release mayfurther include a field (e.g., SPS configuration index field) that isnot included in the V2X sidelink dynamic DCI.

Among the fields included in the DCI format, in case each of thepre-determined specific fields has a pre-determined value (sequence),the UE may validate the corresponding DCI format as the DCI format forV2X sidelink SPS activation/release.

For example, in case of an SPS release, since an actual SPS datatransmission does not occur, values of the DCI fields (MCS, RV, resourceblock assignment field, and so on) that are related to resourceassignment become unneeded (or unnecessary) values. Therefore, thevalues of the DCI fields that are related to resource assignment may beconfigured as a pre-determined sequence (e.g., all of the values may beset to 0).

The following table shows a mapping example between a cyclic shift DM-RSfield and a V2X uplink SPS configuration index.

TABLE 6 Value of SPS configuration field of a sidelink (E)PDCCH Usage‘000’ Sidelink dynamic scheduling ‘001’ Sidelink SPS configuration 0 forV2X ‘010’ Sidelink SPS configuration 1 for V2X ‘011’ Sidelink SPSconfiguration 2 for V2X ‘100’ Sidelink SPS configuration 3 for V2X ‘101’Sidelink SPS configuration 4 for V2X ‘110’ Sidelink SPS configuration 5for V2X ‘111’ Sidelink SPS configuration 6 for V2X

In order to save DCI fields in DCI Format 5, there may exist someflexibility in the resource assignment for SPS. In order to schedule theindicated sidelink V2V (including the SPS), the bit size of the DCIfield may be reduced according to a position correlation between the SAand data. When SPS data are transmitted in accordance with the T-RPTpattern, a T-RPT field, a frequency hopping flag field, and/or an RVfield may be used. However, when each SPS (re-)transmission follows theDCI, such DCI fields may not be needed.

If a time gap between a SA transmission and a data transmission isinformed in advance or fixed, a time indication field corresponding tothe data transmission (a field announcing (or informing) a timing offsetbetween the SA and the data) will not be needed. Additionally, if the SAcan announce (or inform) a start position of a frequency assignment ofthe data, it may suffice to have the resource block assignment fieldthat is included in the DCI to inform only the RB size of thecorresponding data. Accordingly, the resource block assignment field maybe reduced to 3 to 7 bits.

Similarly, by performing subchannelization of the data region, a largernumber of DCI bits may be saved. For example, by dividing (orsubchannelizing) the data region to 10 sub-channels, the resource blockassignment field may be reduced to 4 bits.

The following table shows an example of changing the fields (DCI fields)being included in the DCI Format 5 for sidelink SPS.

TABLE 7 when there is no T- when there is no T- RPT and RB RPT, and RBassignment field DCI field for when there is assignment field indicatessub DCI format 5 no when there is indicates only RB channel index (e.g.for sidelink SPS modification no T-RPT size 10 subchannels) Freq.Hopping 1 1 1 1 Flag RB assign  5~13  5~13  3~7 4 TPC 1 1 1 1 SAresource 6 6 6 6 T-RPT 7 SPS X 3 3 3 configuration Total size 20~2816~24 14~18 15

DCIs including different SP configurations may be associated to a commonRNTI, and the corresponding RNTI may be different from the RNTI fordynamic scheduling.

The DCI Format 5 may undergo minor changes and may then be used for a(n)(E)PDCCH for sidelink SPS trigger/release.

The resource block assignment field and the T-RPT field for the DCIFormat 5 may be excluded or be reduced in length in accordance withtheir relation with the time/frequency position between the SA and thedata.

In summary, 1) after receiving a(n) (E)PDCCH message for SPStrigger/release, the UE may feed-back an ACK/NACK. 2) DCIs havingdifferent SP configurations may be associated to a common RNTI, and, inthe point of view of the UE, the corresponding RNTI may be differentfrom the RNTI that is used for dynamic scheduling. 3) The DCI Format 5may undergo minor changes and may then be used for a(n) (E)PDCCH forsidelink SPS trigger/release. 4) The resource block assignment field andthe T-RPT field may be excluded or be reduced in length in accordancewith their relation with the time/frequency position between the SA andthe data.

Hereinafter, a method for efficiently supporting uplink SPS operationswill be described in detail.

As described above, in case of the Mode 1 SPS, the base station mayconfigure a plurality of (multiple) SPS configurations to the UE. A SPSconfiguration specific MCS and a SPS configuration specific cycle periodmay be configured. The base station may trigger/release dynamicallydifferent SPS configurations by using the PDCCH/EPDCCH. Before atransmission time point that is associated to the SPS configuration, theUE may announce to the base station that the UE will not be performingdata transmission.

<(E)PDCCH Design for Uplink SPS>

The uplink SPS and the sidelink SPS are similar in the aspect that theyare both related to V2X message transmission and that the resources areconfigured by the base station. Therefore, it will be preferable thatthe uplink SPS and the sidelink SPS have a common design.

In the uplink SPS (E)PDCCH design, a DCI for a UL grant (e.g., DCIFormat 0) may become the basic DCI. Considering the characteristics ofSPS, the uplink SPS (E)PDCCH should differentiate its SPStrigger/release. Additionally, a plurality of SPS configurations shouldbe supported. For this, it may be required to change some (or part) ofthe fields, among the fields included in the existing DCI format, andthen to adopt the new field (SPS configuration index). Herein, the SPSconfiguration fields may be expressed as indexes of the SPSconfiguration. For example, the SPS configuration field may be expressedas an index of the SPS configuration. For example, in case 7 SPSconfigurations exist, the size of an SPS configuration field may beequal to 3 bits.

If the cyclic shift DM RS field is used as an SPS configuration index,each of the remaining values excluding ‘000’ may be matched to SPSconfiguration 0 to 7. With the exception of the cyclic shift DM RSfield, the performance of the V2X uplink SPS trigger/release may besimilar to the performance of an LTE uplink SPS.

The following table shows an exemplary mapping between values of acyclic shift DM RS field and a V2X uplink SPS configuration index.

TABLE 8 Value of Cyclic shift DM RS field in DCI format 0 Usage ‘000’Existing LTE uplink SPS ‘001’ Uplink SPS configuration 0 for V2X ‘010’Uplink SPS configuration 1 for V2X ‘011’ Uplink SPS configuration 2 forV2X ‘100’ Uplink SPS configuration 3 for V2X ‘101’ Uplink SPSconfiguration 4 for V2X ‘110’ Uplink SPS configuration 5 for V2X ‘111’Uplink SPS configuration 6 for V2X

The SPS configuration field may also be expressed as a bitmap (e.g., abitmap of 8 bits). This case is preferable for synchronized managementand operation of a plurality of SPS configurations.

<Processing Collision Between Different SPS Configurations>

In the uplink SPS, how to process a change in a message arrival patternmay be an important issue. Firstly, if a message arrival pattern ischanged, the UE may announce (or notify) such change to the base stationso that appropriate actions can be taken.

The UE may announce to the base station that the UE will not betransmitting any data before the transmission time point beingassociated with the SPS configuration. The UE may announce that it willnot be transmitting any data during one SPS transmission opportunity, orthe UE may announce that it will not be transmitting any data throughoutthe SPS transmission opportunities, i.e., a relatively long period oftime according to the SPS configuration.

In case of the latter, a UE report may be viewed as a type of SPSconfiguration change/release request. More specifically, in case themessage arrival pattern is changed because the UE has not used aparticular SPS configuration during a particular period of time, the UEmay report this situation to the base station so that the base stationcan activate another SPS configuration that is appropriate to thechanged message arrival pattern. The report may be provided through ahigher layer signal in order to prevent an excessive uplink overhead.

In case of the former, a UE report may be viewed as a type of‘verification of a single transmission opportunity’. The base stationmay know which SPS transmission opportunity is actually being used bythe UE.

The verification may correspond to a positive verification or a negativeverification. In case the verification corresponds to a positiveverification, the corresponding report is transmitted when the UEtransmits data, and if there is no positive verification, it may beinterpreted that there is not data transmission. In this case, thecorresponding resources may be used for other purposes.

In case the verification corresponds to a negative verification, thecorresponding report is transmitted when the UE does not transmit anydata. Among the two verification methods, it may be preferable to usethe positive verification method. This is because the correspondingreport may reduce the number of transmission sessions that are carriedout for transmitting the report. The positive verification isadvantageous in that the number of verification messages that aretransmitted is not greater than the actual SPS data transmissions.

Most particularly, in case a plurality of SPS configurations areconfigured to the UE, this advantage becomes clearer. For example, inorder to process a change in the message size, if a negativeverification is used, the UE will be required to transmit a negativeverification before each of the SPS transmission opportunities that arenot being used. Conversely, if the positive verification indicates theSPS configuration that is actually being used, it may be generalizedthat the positive verification selects a SPS configuration during eachdata transmission. For example, a PUCCH resource may be assigned to theUE, and an index of the SPS configuration that is to be used during anext data transmission may be included in the PUCCH transmission.

FIG. 17 shows an example where 2 reports are used at the same time. TheUE may configure 3 cycle periods, i.e., 1000, 500, and 100 ms havingdifferent SPS configurations. The UE may first be instructed to activateSPS configuration #1. If the message generation cycle period is changedto 100ms, the UE may report a change request to the base station, andthe base station may release the SPS configuration #1. Thereafter, thebase station may activate SPS configuration #3. Accordingly, the messagegeneration cycle period may be changed to 500ms. The UE may have thedata that are intended to be transmitted during several SPS transmissionopportunities. At this point, although the verification may correspondto a positive verification, the data are not transmitted. When the UErecognizes such situation, the UE may report another change request tothe base station, and the base station may then activate SPSconfiguration #2.

A report that is related to a sidelink transmission may have a lowerpriority level as compared to other uplink transmissions. For example,if the UE schedules an ACK/NACK transmission or a PUSCH transmission,the verification of the SPS transmission may be dropped.

Since the base station may know when the UE transmits the verification,the base station may prevent the verification from being dropped due tothe scheduling. If the transmission of the verification is dropped dueto the scheduling of the base station, in order to avoid breaking (ordisobeying) the latency requirements, the UE may transmit data duringthe corresponding SPS transmission opportunity. When the base stationbecomes informed (or aware) that the verification transmission has beendropped, the base station may not use the corresponding SPS resource foranother purpose.

Meanwhile, when performing V2X Mode 1 communication, a method allowing aV2X transmission UE to determine a (V2X data transmission related) MCSvalue as a UE implementation (or independently) may be supported.

Herein, for example, in case the same DCI format (or DCI format havingthe same configuration) (e.g., a similar role as the (existing) “DCIFormat 5”) (this will be referred to as Mode 1_DCI) is used for a V2XMode 1 communication scheduling that is based on a “dynamic format”and/or a “SPS format”, an MCS field may be defined.

For example, if an MCS field value within the Mode 1_DCI that isreceived from the (serving) base station indicates apre-configured(/signaled) specific value (or a “reserved state”), a V2XUE may be capable of determining a (V2X data transmission related) MCSvalue as a UE implementation (or independently) (e.g., if the MCS fieldvalue within the Mode 1_DCI indicates another value (other than theabove-mentioned value), V2X data transmission may be performed inaccordance with the corresponding MCS value).

For example, a field indicating a PSSCH(/PSCCH) DM-RS (sequence) related“cyclic shift (CS) index” value (and/or a sequence generation relatedseed value (e.g., sequence group number (U), a basic sequence number(V))) within the DCI format that is related to the V2X Mode 1communication scheduling may be (additionally) defined.

For example, instead of (additionally) defining a Mode 1_CSFD within theDCI format that is related to the V2X Mode 1 communication scheduling,(A) if a PSSCH(/PSCCH) DM-RS (sequence) related “cyclic shift (CS)index” value (and/or a sequence generation related seed value) isreceived from the (serving) base station via RRC signaling, the V2Xtransmission UE may be capable of generating a PSSCH(/PSCCH) DM-RS(sequence) in accordance with the corresponding value.

(B) Alternatively, if a PSSCH(/PSCCH) DM-RS (sequence) related “cyclicshift (CS) index” value (and/or a sequence generation related seedvalue) is not received from the (serving) base station (via RRCsignaling), the V2X transmission UE may be capable of determining thePSSCH(/PSCCH) DM-RS (sequence) related “cyclic shift (CS) index” value(and/or a sequence generation related seed value) as a UE implementation(or independently).

For example, a type(/range) of the “cyclic shift (CS) index” value(and/or a sequence generation related seed value) that can be determinedas a UE implementation (or independently) may bepre-configured(/signaled).

The PSSCH DM-RS (sequence) related “cyclic shift (CS) index” value(and/or a sequence generation related seed value), which is determinedin accordance with the above-described rule, may also be signaledthrough a (specific) field within the SA (e.g., a role that is similarto the (existing) “SCI Format 0”).

For example, a (Mode 1) PSSCH(/PSCCH) DM-RS (sequence) (“cyclic shift(CS) index” value) may be generated(/determined) through a function inwhich a pre-configured(/signaled) a “SPS format” based V2X Mode 1communication related RNTI (SPS-RNTI) value (and/or a “dynamic format”based V2X Mode 1 communication related RNTI (DYM-RNTI) value) is definedas an input parameter (e.g., “FLOOR(SPS-RNTI/2) MOD 8” (herein, “FLOOR(X)” and “A MOD B” respectively indicate a function drawing out aninteger that is equal to or smaller than X and a function drawing out aremainder value from A divided by B)).

In a case where a V2X UE performing the “SPS format” based V2X Mode 1communication has received configuration(/signaling) of a(time/frequency) resource so that the corresponding V2X UE canrespectively perform (TDM) transmission of the PSCCH and PSSCH over Wand Q number of times, (A) if a pre-configured(/signaled) S^(th) (e.g.,“S=1”) PSCCH transmission is performed and a (pre-defined) SPS releaseDCI format (this will be referred to as SPS_RELFMT) is received beforean interconnected PSSCH transmission (in subframe #N) (and/or if theSPS_RELFMT is received (in subframe #N) while performing a (PSCCH/PSSCH)transmission operation that is related to a (specific) transmissionblock), (based on an assumption that the SPS resource has been released(after a time point including (or not including) subframe #(N+4))settings may be made so that the subsequent transmission operations arenot performed (through the corresponding SPS resource) (or settings maybe made so that only the (specific) transmission block relatedtransmission can be performed(/completed)).

Herein, for example, for the release of the pre-configured(/signaled)(Mode 1) SPS resource and/or the suspension of the (PSCCH/PSSCH)transmission operation that is based on the corresponding (SPS) resourcesettings may be made so that SPS_RELFMT can be received before apre-configured(/signaled) value (e.g., “4 ms”) from (at least) a firstPSCCH transmission point that is related to a (specific) transmissionblock.

In a case where a V2X UE performing the “dynamic format” based V2X Mode1 communication has received configuration(/signaling) of a(time/frequency) resource within a plurality of subframes for thetransmission of the (specific) transmission block, if a DCI format(DYN_RELFMT) indicating the suspension of a (pre-defined) dynamictransmission is received (Subframe #J) while performing the(PSCCH/PSSCH) transmission operation that is related to the (specific)transmission block, (based on an assumption that the dynamic resource isnot valid (or effective) (after a time point including (or notincluding) subframe #(J+4)) settings may be made so that the subsequenttransmission operations are not performed (or settings may be made sothat only the (specific) transmission block related transmission can beperformed(/completed)).

Herein, for example, for the invalidation (release) of thepre-configured(/signaled) (Mode 1) dynamic resource and/or thesuspension of the (PSCCH/PSSCH) transmission operation that is based onthe corresponding (dynamic) resource settings may be made so thatDYN_RELFMT can be received before a pre-configured(/signaled) value(e.g., “4 ms”) from (at least) a first PSCCH transmission point that isrelated to a (specific) transmission block.

For example, in case the V2X UE has received from its (camping) basestation(/cell) a configuration(/signaling) instructing the V2X UE toprioritize the GNSS timing(/synchronization) (over the base stationtiming(/synchronization)) within a specific carrier, if a (other) basestation(/cell) is detected within the corresponding (specific) carrier(e.g., this may be understood that the V2X UE is positioned within thecoverage of the detected (other) base station(/cell)), and if thecorresponding (other) base station(/cell) is sending aconfiguration(/signaling) instructing the UE to prioritize the basestation timing(/synchronization), (if the V2X UE is positioned (atleast) within the coverage of the (other) detected base station(/cell))the V2X UE may prioritize the base station timing(/synchronization).

The V2X UE may also receive configuration(/signaling) from its (camping)base station(/cell) indicating for which base station(/cell) within thespecific carrier the base station timing(/synchronization) or the GNSStiming(/synchronization) is to be prioritized.

In case a HARQ-ACK feedback corresponding to a ‘sidelink (and/oruplink)-SPS (activation/release) DCI’ reception is defined, in case of a‘NACK’, the V2X UE may be capable of performing a ((excluded) poolbased) Mode 2 (fallback) operation (during a pre-configured(/signaled)period of time)).

In case a plurality of ‘sidelink (and/or uplink) SPSprocesses(/configurations)’ are configured(/signaled) (to a specific V2XUE), a(n) (independent) (“open-loop” (and/or “closed-loop” (e.g.,“separate TPC accumulation”))) power control may be managed and operatedper ‘sidelink (and/or uplink) SPS process(/configuration) (set)’,through a pre-defined DCI format (e.g., “DCI 3(/3A)” Format) (this willbe referred to as V2XSPS_TPCDCI).

A plurality of (TPC) fields (having a pre-configured(/signaled) size)may exist within the (corresponding) V2XSPS_TPCDCI, and aninterconnection(/linkage) information between a specific (TPC) fieldindex and a ‘(specific) sidelink (and/or uplink) SPSprocess(/configuration)’ (and/or a ‘cell index in which a (specific)sidelink (and/or uplink) SPS process(/configuration) isconfigured(/signaled)’ and/or a ‘V2X UE ID’) may be configured through apre-defined (higher layer(/physical layer)) signaling.

The (corresponding) V2XSPS_TPCDCI may (exclusively) indicate (orinstruct) power control information (in a “cross carrier(/cell)scheduling format) corresponding to another cell (e.g., a secondarycell) (other than a primary cell (and/or a cell in which theV2XSPS_TPCDCI is received (e.g., a (primary cell) common searchspace))).

For the (corresponding) V2XSPS_TPCDCI, (A) a (new) V2XTPC-RNTI valuemaybe configured(/signaled) and/or (B) the existing (WAN communicationrelated) TPC-PUSCH-RNTI (and/or TPC-PUCCH-RNTI) value may be (sharedand) re-used. In case of the latter, a field (e.g., “1 bit”) fordifferentiating the corresponding DCI from the (existing) WANcommunication related TPC DCI within the V2XSPS_TPCDCI may be defined.The V2XSPS_TPCDCI related (payload) size may be defined to identicallymatch the size of the (existing) WAN communication related TPC DCI(e.g., “DCI 3(/3A)”) (which is transmitted from the same(common(/UE-specific)) search space (SS) region) (for example, when theV2XSPS_TPCDCI related (payload) size is relatively smaller, zero padding(and/or padding with a pre-configured(/signaled) value)) may beperformed until the corresponding size becomes equal to the (payload)size of the (existing) WAN communication related TPC DCI).

Configuration(/signaling) may be made so that “separate TPCaccumulation” operations can be applied per ‘sidelink (and/or uplink)SPS process(/configuration)’. A different (or independent) “open-loopparameter (e.g., ‘P_0’ and/or ‘ALPHA’, and so on)” may beconfigured(/signaled) per ‘sidelink (and/or uplink) SPSprocess(/configuration)’ and/or a different (or independent) powercontrol parameter may be configured(/signaled) within a (single)specific ‘sidelink (and/or uplink) SPS process(/configuration)’ per (V2Xmessage) PPP (and/or V2X message type(/characteristic (e.g., cycleperiod))), thereby allowing the V2X UE to apply the interconnected powercontrol parameter when performing transmission of the specific (V2Xmessage) PPP (and/or V2X message type(/characteristic (e.g., cycleperiod))) (within the corresponding ‘sidelink (and/or uplink) SPSprocess(/configuration)’).

Herein, for example, the (independent) (“open-loop” (and/or“closed-loop” (e.g., “separate TPC accumulation”))) power control per‘sidelink (and/or uplink) SPS process(/configuration) (set)’ may beimplemented by designating a “power offset value” within (part (or allof)) the ‘sidelink (and/or uplink) SPS process(/configuration) (set)’through a pre-defined (higher layer(/physical layer)) signaling.

As another example, in case a plurality of ‘sidelink (and/or uplink) SPSprocesses(/configurations)’ are configured(/signaled), the “open-loop”(and/or “closed-loop” (e.g., “separate TPC accumulation”))) powercontrol operation(/parameter) may be commonly applied(/managed andoperated) between the plurality of ‘sidelink (and/or uplink) SPSprocesses(/configurations)’.

Since the examples of the above-described proposed methods may beincluded as one of the implementation methods of the present invention,it will be apparent that the corresponding examples can be viewed (orconsidered) as a type of the proposed methods. Additionally, althoughthe above-described proposed methods may be independently implemented,the above-described proposed methods may also be implemented in acombined (or integrated) form of parts of the proposed methods. Forexample, although the present invention is described based on a 3GPPLTE/LTE-A system for simplicity in the description, the scope of systemsin which the proposed methods can be applied may be extended to diversesystems other than the 3GPP LTE/LTE-A system. For example, the proposedmethods according to the present invention may also be extendedlyapplied to D2D communication. Herein, for example, D2D communicationrefers to performing communication between a UE and another UE by usinga direct wireless channel. And, herein, for example, although the UErefers to a user device, in case a network equipment, such as a basestation, transmits/receives signals according to a communication methodperformed between UEs, the corresponding network equipment may also beviewed as a type of UE. Additionally, for example, the proposed methodsaccording to the present invention may also be limitedly applied only inMode 2 V2X operations (and/or Mode 1 V2X operations).

Additionally, for example, in the proposed methods according to thepresent invention, the ‘(sidelink and/or uplink-SPS)(activation/release) DCI’ may be limitedly transmitted only through a‘(PDCCH or EPDCCH) UE-specific search space’ (or ‘PDCCH common searchspace’).

Additionally, for example, in the proposed methods according to thepresent invention, the ‘(sidelink and/or uplink-SPS)(activation/release) DCI’ may also be interpreted as a ‘Mode 1 DCI’(that is received from base station) (announcing PC5 (V2V) SPS relatedscheduling information).

FIG. 18 is a block diagram illustrating a UE in which the embodiments ofthe present invention are implemented.

Referring to FIG. 18, a UE 1100 includes a processor 1110, a memory 1120and a radio frequency (RF) unit 1130. The processor 1110 implements theproposed functions, processes and/or methods.

The RF unit 1130 is connected to the processor 1110 to transmit andreceive radio signals.

The processor may comprise an application-specific integrated circuit(ASIC), other chipset, logic circuitry and/or data processing device.The memory may include read-only memory (ROM), random access memory(RAM), flash memory, memory cards, storage media, and/or other storagedevices. The RF unit may include a baseband circuit for processing theradio signal. When the embodiment is implemented in software, theabove-described techniques may be implemented with modules (processes,functions, and so on) that perform the functions described above. Themodule may be stored in the memory and may be executed by the processor.The memory may be internal or external to the processor, and may becoupled to the processor by various well known means.

What is claimed is:
 1. A method for transmitting downlink controlinformation for sidelink scheduling in a wireless communication system,comprising: generating a sidelink SPS activation/release DCI instructingan activation or release of a sidelink semi-persistent scheduling (SPS);and transmitting the sidelink SPS activation/release DCI to a userequipment (UE), wherein the sidelink SPS activation/release DCI furtherincludes a sidelink SPS configuration index field and a sidelink SPSactivation/release field that do not exist in a sidelink dynamic DCI,the sidelink dynamic DCI performing dynamic scheduling of a sidelink. 2.The method of claim 1, wherein the sidelink SPS configuration indexfield includes information indicating one of a plurality of sidelink SPSconfigurations.
 3. The method of claim 1, wherein a total bit size ofthe sidelink SPS activation/release DCI is larger than a total bit sizeof the sidelink dynamic DCI.
 4. The method of claim 1, wherein thesidelink SPS configuration index field is configured of 3 bits.
 5. Themethod of claim 1, wherein the sidelink SPS activation/release field isconfigured of 1 bit.
 6. A wireless device, comprising: a radio frequency(RF) unit transmitting and receiving radio signals; and a processorbeing operatively connected to the RF unit, wherein the processor isconfigured: to generate a sidelink SPS activation/release DCIinstructing an activation or release of a sidelink semi-persistentscheduling (SPS), and to transmit the sidelink SPS activation/releaseDCI to a user equipment (UE), wherein the sidelink SPSactivation/release DCI further includes a sidelink SPS configurationindex field and a sidelink SPS activation/release field that do notexist in a sidelink dynamic DCI, the sidelink dynamic DCI performingdynamic scheduling of a sidelink.
 7. The wireless device of claim 6,wherein the sidelink SPS configuration index field includes informationindicating one of a plurality of sidelink SPS configurations.
 8. Thewireless device of claim 6, wherein a total bit size of the sidelink SPSactivation/release DCI is larger than a total bit size of the sidelinkdynamic DCI.
 9. The wireless device of claim 6, wherein the sidelink SPSconfiguration index field is configured of 3 bits.
 10. The wirelessdevice of claim 6, wherein the sidelink SPS activation/release field isconfigured of 1 bit.